World: r3wp
[!REBOL3 Proposals] For discussion of feature proposals
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BrianH 9-Nov-2010 [90x2] | If you are claiming that there are no such phrases, fine. But assuming that such cases were possible was the premise that led to the "you have no recourse". |
no such phrases -> no such cases | |
Andreas 9-Nov-2010 [92x2] | Which is hypothetical as it is easy to show there are no such cases. So inner functions have nothing to do with it. |
And even if you insist on that hypothesis, the claim is still wrong. | |
BrianH 9-Nov-2010 [94x3] | Sorry, inner functions are the easiest way to implement certain things. And we need to consider that too-complex functions or ones that use arcane workarounds are getting rejected for that reason alone nowadays. Most of the native changes in the last 3 releases of R3 have been to deal with situations like this. For these proposals, easy trumps possible. |
So even the FOREACH workaround would be enough to prompt a change now. For that matter, the most recent module system rewrite was specifically for that reason. The new module system doesn't do anything that the pre-108 rewrite didn't do, but it is easier to use. Easy by default is the top priority. | |
The only reason definitional-only might be chosen is because it is easier to understand than the other models. That alone might trump the places where it still doesn't work. I hope not, because the "option to not rebind RETURN and EXIT" is really simple to specify and much easier to do than the workarounds that you have to do if you don't have that option, workarounds like your BIND + DO, especially when you consider 'self issues that prevent you from using objects for this kind of thing (hence the FOREACH). | |
Andreas 9-Nov-2010 [97x2] | So the real disadvantage in the "inner function" paragraph is that you can not write a function which does not rebind RETURN. |
(Or at least that's the claim.) | |
BrianH 9-Nov-2010 [99x2] | Yes. I'm sorry for the confusing phrasing. |
So assume that in this case "not possible" could in some cases mean "not possible to get accepted as a mezzanine because it's too Scheme-like" or "not possible for a regular programmer to come up with a workaround like this", because both limitations have real examples that have already manifest. | |
Andreas 9-Nov-2010 [101] | More precisely, the disadvantage is that we don't have an any-function! constructor which does not rebind RETURN in the function body. |
BrianH 9-Nov-2010 [102x3] | And the claim is false because of the workaround with the direct function value references, which I came up with later. Only the words are rebound. |
We actually need that option for both function! and closure! types, because of their different contexts. It is easier to add this as an option than as different types. | |
Especially since Carl is the one who suggested options in the first place, so we know it's possible to implement. | |
Andreas 9-Nov-2010 [105] | That's why I said any-function!. |
Ladislav 9-Nov-2010 [106] | not possible to get accepted as a mezzanine because...not possible for a regular programmer to come up with a workaround like this" - why, then, was my CLOSURE constructor accepted? |
BrianH 9-Nov-2010 [107] | No, it would need two added function types, not just one. And names for those types, and names for the wrapper functions that create those types, and so on. An option is easier. |
Andreas 9-Nov-2010 [108] | We are talking past each other. |
BrianH 9-Nov-2010 [109] | That was a backport, Ladislav. R2 has more lax standards. We are trying to cut back on that in R3, but R2 is a lost cause. |
Andreas 9-Nov-2010 [110] | The disadvantage is that we don't have a function constructor which does not rebind return in the function body. |
BrianH 9-Nov-2010 [111x2] | If you want to talk about intimidating R2 functions, look at APPLY or MAP-EACH. Neither of those would be accepted for R3. |
Agreed, Andreas. I was just saying that a spec option is a better solution to that problem than new datatypes. | |
Andreas 9-Nov-2010 [113] | Yeah, and as I did not suggest new datatypes, I was wondering where that came from. |
BrianH 9-Nov-2010 [114x2] | we don't have an any-function! constructor... |
Guess I misinterpreted that :( | |
Andreas 9-Nov-2010 [116x2] | Which was meant to imply that we have neither a constructor for closure! nor for function! nor for any other user-definable function type :) |
Misleading, though. Sorry for that. | |
BrianH 9-Nov-2010 [118x4] | One of the goals of the native changes in R3 is to cut down on the need for arcane workarounds in regular REBOL code. For every arcane workaround that you might see in a mezzanine, you will see the same workaround need to be done over and over again in user code. Usually badly. There have been a host of native changes to make regular REBOL code easier to write and read and cleaner to look at. We even got more of these in the last 3 releases. |
For that matter, that is what the call for idioms is for. | |
We can backport stuff from R3 to R2, but what we can't backport is simplicity :( | |
Btw, Ladislav, thanks again for the CLOSURE constructor. If you hadn't come up with that great a solution then R2 likely wouldn't have gotten closures at all, and none of the other fake datatypes would have made it in either, which would have been a real tragedy if we missed out on the typeset! stuff. | |
Ladislav 9-Nov-2010 [122] | If I did not came with CLOSURE, not even R3 would have gotten it, I bet |
BrianH 9-Nov-2010 [123x2] | True, but you notice that R3 got it as native. We are trying to hide complexity. |
Strangely enough, when I backported CLOSURE to R2 I had forgotten that you had written a version, but what I came up with ended up being the same code, exactly. So I attribute it to you through my unconscious :) | |
Andreas 9-Nov-2010 [125x2] | As an additional advantage, the meaning and expected behavior of '''return''' and '''exit''' from code blocks is clear with dynamic return, since dynamic return is defined in relation to the flow of calls to functions rather than in terms of lexical scoping. That is highly debatable. |
Especially if already using lexical scoping terminology, there's nothing that makes dynamic scoping instrinsically more clear than lexical scoping. And even when limiting this discussion to REBOL, where lexical scope is only faked, that does not make the concept in any way less "clear" than it's non-faked dynamically scoped counterpart. | |
BrianH 9-Nov-2010 [127x4] | It is clear *once you accept the idea of dynamic scope*, which is an inherent part of the semantics of all dynamic escape functions. And that limitation is listed as a disadvantage in the same model. |
Disadvantage: "Some people seem to question or have trouble understanding dynamic return as a concept, let alone its benefits." | |
It's a *real* disadvantage. | |
Just got done with the style makeover and rewording of some of the models based on the misunderstandings above. | |
Andreas 9-Nov-2010 [131] | So to sum up. Advantage: dynamic scoping is more clear. Disadvantage: dyanmic scoping is less clear. |
BrianH 9-Nov-2010 [132] | One scoping model is more clear. Two scoping models is less clear. Refresh the page. |
Andreas 9-Nov-2010 [133] | Both scoping models are part of REBOL. So my summary still stands. |
BrianH 9-Nov-2010 [134x2] | I find it more confusing to understand how REBOL works when I let myself think it really has lexical scoping. It is much more clear when i realize that it doesn't, not really. |
The downside to adding definitional scoping of returns is that it enhances the illusion of lexical scoping, which enhances the confusion. | |
Andreas 9-Nov-2010 [136x2] | Or reduces the generall mess caused by too much dynamic scope. |
Definitional scope is a a major part of what makes REBOL usable at all. Like it or not. | |
BrianH 9-Nov-2010 [138x2] | But there are too many upsides to definitional return to ignore. So if it makes return less useful, at least it makes it easier. |
I prefer the "Definitional return with an option to not redefine RETURN and EXIT, dynamic return as a fallback" model because it is the most useful. But I would be willing to accept the "Definitional return with an option to not redefine RETURN and EXIT, no dynamic return" model if it becomes the community consensus - it would mean fewer bug reports, at least from users unfamiliar with REBOL, particularly R2. | |
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